In the past, Tyson has thrown shade on Elon Musk’s plans to go to Mars. Last year, in an interview with The Verge, he described the idea of SpaceX leading the space race as a “delusion.” He made the case that private companies are not equipped to handle interplanetary travel, given the risks (including inevitable death), the costs involved, and the struggle to make a profit.

But in an appearance on CNBC after Musk’s keynote at the International Astronautical Congress in Mexico earlier this week, Tyson gave Musk credit for “putting his money where his mouth is.” He said that Musk is creating a business model out of space exploration and using his corporations to make this happen. “You got to listen to this guy,” he quipped.